Michaela Schmitz-Eiberger

Apple (Malus domestica L. Borkh.) Allergen Mal d 1: Effect of Cultivar, Cultivation System, and Storage Conditions

It has been reported on the basis of skin prick tests and gene expression studies that apple cultivars differ in their allergenic potential. Only a few studies have tried to measure the amount of the major apple allergen Mal d 1 so far. Mal d 1 belongs to the pathogenesis-related proteins, a family of proteins that are induced by pathogens and environmental stress. Due to cross-reactivity between Bet v 1 and proteins present in several plant-derived foods, birch pollen allergic patients develop food allergies, most frequently to apples. Mal d 1 content was quantified in different apple cultivars, cultivated at the research stations Klein-Altendorf and Bavendorf, dependent on cultivation method and storage conditions by sandwich-ELISA. Apple cultivars differ considerably in their Mal d 1 content. A high variability in Mal d 1 content was determined within one cultivar and between the two locations for the same apple cultivar. In most cases organically cultivated fruit showed lower Mal d 1 content in comparison to fruit from integrated production. At harvest the detected concentration of Mal d 1 was low, but during storage the Mal d 1 content increased significantly.

Calcium deficiency - Influence on the antioxidative defense system in tomato plants

Summary In this study the influence of a deficient calcium supply on the antioxidative defense system in Lycopersicon lycopersicum leaves was investigated. Trials were performed in the greenhouse employing soilless culture technique. For the induction of calcium deficiency, calcium content in the nutrient solution was reduced from 2.9 mmol/L to 0.29 mmol/L. Within 6 weeks fruits and leaves developed distinct calcium deficiency symptoms. Chlorophyll fluorescence parameters, e.g. Fm and Fv/Fm, chlorophyll and tocopherol contents dropped below control level; also, superoxide dismutase activity was reduced. Additionally, malondialdehyde as a degradation product of lipid peroxidation increased in the calcium deficient leaves. Spray application of formulated CaCl 2 solution on a weekly basis reduced blossom-end rot symptoms to about 50 percnt;. Furthermore, chlorophyll fluorescence parameters Fm and Fv/Fm as well as chlorophyll and tocopherol contents were less affected than in the calcium deficient group. No differences in malondialdehyde production could be established. SOD activity was higher in the Ca 2+ -treated leaves, while PO activity was lower compared to calcium deficient leaves.

Effects of NaCl on surface properties, chlorophyll fluorescence and light remission, and cellular compounds of Grewia tenax (Forssk.) Fiori and Tamarindus indica L. leaves

Seedlings of the salt-tolerant plant grewia [Grewia tenax (Forssk.) Fiori] and the moderately salt-tolerant tamarind (Tamarindus indica L.) were grown under controlled conditions and treated daily with NaCl solutions to investigate mechanisms of tolerance to salinity. Leaf micromorphology, cuticular wax load, chlorophyll fluorescence and light remission, as well as antioxidative potential were evaluated. As confirmed by energy-dispersive X-ray microanalysis in both species, absorption of sodium and chlorine increased with rising NaCl concentration in the treatment solution. In parallel, accumulation of calcium in grewia leaves was strongly reduced, leading to less crystals of calcium oxalate in leaf tissue. In grewia the cuticular wax load, chlorophyll content, and electron transport rate (ETR) were significantly reduced by comparatively low NaCl concentrations. In tamarind, in contrast, wax load and ETR were not significantly affected, while the decrease of chlorophyll content was less pronounced. Measurements of the antioxidative capacity and the imbalance between values of lipophilic and hydrophilic extracts at different NaCl concentrations confirmed that grewia is more salt tolerant than tamarind. This higher tolerance degree seemed to be associated with grewias’ more efficient scavenging of free radicals and the regulation of the antioxidative potential in lipophilic and hydrophilic extracts.

Inhibitory effects of sub-optimal root zone temperature on leaf bioactive components, photosystem II (PS II) and minerals uptake in Trichosanthes cucumerina L. Cucurbitaceae

We hypothesized that sub-optimal root zone temperature (RZT) will cause a reduction in the bioactive components contents, adversely affect PS II and hinder uptake/partitioning of mineral elements in the “Light Green Variant” of the African snake tomato (Trichosanthes cucumerina L.). Three RZT temperatures (20, 25 and 30°C) were evaluated in a digitally controlled growth chamber. Results showed that for all the mineral nutrients analyzed (Ca, Mg, P, K, Fe and Mn), the amounts absorbed by the plant increase as RZT increases with each nutrient displaying different characteristics with respect to the quantity partitioned into root, stem and leaf at the different RZT. At sub-optimal RZT (20°C), significantly higher amounts of Ca and K were found in the root, whereas at normal RZT (25 and 30°C) higher amounts of Ca were recorded in the stem, and about 50% of the amounts in the stem were found in the leaves. For all the RZT, the amounts of Mg in the leaves were significantly higher than in the root and stem, while the amounts in the stems were also significantly higher than the amounts in the roots. At normal RZT (25 and 30°C) almost equal amounts of P were present in the root, stem and leaf. The amounts of phenolics, ascorbic acid, chlorophyll a and b and total chlorophyll increase as the RZT increases. Photosystem analyses showed that at 30°C the Fv/Fm (relative photochemical efficiency) was 0.76, while at 20 and 25°C the values were 0.35 and 0.60, respectively. The Fv/Fm value (0.35) obtained at 20°C confirmed the adverse effects of sub-optimal RZT on the photosystem II (PS II). Photosynthetic measurements showed that as the RZT increased, A (net photosynthetic efficiency), E (transpiration rate), Ci (intercellular carbon dioxide concentration) and g1 (stomata conductance) also increased. We postulate that the higher E and g1 at high RZT have a great physiological implication on plant performance, because transpiration cooling would be improved, especially during the summer; but the lost water must be complemented by adequate irrigation. The totality of the results confirm our hypothesis that sub-optimal RZT will cause a reduction in the bioactive components contents, adversely affect PS II and hinder uptake/partitioning of mineral elements in T. cucumerina.

Enhancing biological efficacy and rainfastness of foliar applied calcium chloride solutions by addition of rapeseedoil surfactants

The efficacy of a homologous series of biodegradable rapeseedoil derivatives (triglyceride ethoxylates; Agnique RSO® series, Cognis, Dusseldorf, Germany) with an average of 5, 10, 30, and 60 units of ethylene oxide (EO) as adjuvants for foliar-applied calcium chloride (CaCl2) was evaluated in Malus domestica L. Borkh. Previous experiments revealed that the surfactants used are not phytotoxic. All the surfactants applied decreased contact angles of spray solutions. The lipophilic surfactants RSO 5 and RSO 10 reduced contact angles more than the hydrophilic ones. Drying time of spray droplets was most prolonged when RSO 5 was added. Our data provide evidence that the most lipophilic surfactant RSO 5 can enhance Ca penetration, which was shown in isolated cuticles of tomato fruits (Lycopersicon esculentum cv. Panovy) as a model system. The surfactant effect was most pronounced during the first 4 h and reached a plateau after 24 h. Rainfastness of Ca on surfaces of Malus domestica leaves was improved when RSO 5 was added to CaCl2 spray solutions. All surfactants applied improved rainfastness of Ca on ’Braeburn’ fruit surfaces compared to the treatment with CaCl2 alone. Under field conditions, leaf/fruit application of CaCl2/RSO 5 led to an increased Ca content in ’Braeburn’ apple fruits and a reduced bitter pit incidence. Steigerung der biologischen Wirksamkeit und Regenfestigkeit von blattapplizierten Calciumchloridlosungen durch Zusatz von Rapsolethoxylaten Die biologische Wirksamkeit von blattapplizierten Calciumchlorid (CaCl2)-Losungen unter Zusatz einer homologen Reihe von Rapsolethoxylaten mit 5, 10, 30 und 60 Ethylenoxid(EO)-Einheiten (Triglyceridethoxylate; Agnique RSO® Serie, Cognis, Dusseldorf, Germany) wurde bei Malus domestica L. Borkh. gepruft. Vorhergehende Untersuchungen haben ergeben, dass die Rapsolethoxylate in der angewandten Konzentration nicht phytotoxisch sind. Alle verwendeten Tenside minderten die Kontaktwinkel der Spritzlosung. Dieser Effekt war bei Zusatz von Rapsolethoxylaten mit kurzen EO-Einheiten (RSO 5, RSO 10) starker als bei Zusatz von lipophilen Tensiden. Die Trocknungszeiten wurden am starksten bei Verwendung des kurzkettigen Tensids RSO 5 verlangert. Die Penetration von Ca durch isolierte Tomatenfruchtkutikeln (Lycopersicon esculentum cv. Panovy) konnte durch Zusatz des lipophileren Tensids RSO 5 gesteigert werden. Die Penetration war wahrend der ersten vier Stunden nach der Applikation am hochsten und erreichte nach 24 h ein Plateau. Die Regenfestigkeit von blattappliziertem Ca wurde nach Applikation von CaCl2 unter Zugabe des Tensids RSO 5 an Apfelsamlingen ebenfalls deutlich erhoht. Alle angewandten Tenside erhohten die Regenfestigkeit von Ca auf Fruchtoberflachen von ,Braeburn’-Fruchten deutlich im Vergleich zu einer Applikation von CaCl2 allein. Freilandversuche ergaben erhohte Ca-Gehalte in ,Braeburn’-Fruchten und ein vermindertes Auftreten der Stippigkeit an Apfelfruchten nach Blatt- und Frucht-Applikationen von CaCl2 unter Zusatz von RSO 5.

Retention and rainfastness of mancozeb as affected by physicochemical characteristics of adaxial apple leaf surface after enhanced UV-B radiation

It is not clear so far whether alteration of leaf micromorphology and surface wax chemistry due to the impact of environmental factors, such as UV-B radiation, affects retention and rainfastness of applied pesticide solutions. In this study; UV-B treated and untreated adaxial leaf surfaces of apple seedlings (Malus domestica Borkh.) were characterized in terms of chemical composition, micromorphological fine structure, hydrophobicity, and wettability. Furthermore, the retention and rainfastness of applied fungicide mancozeb were studied. The samples were examined 0, 24 and 48 h after ultraviolet (UV)-B radiation (0.022 kW m− 2 for 150 min) The total wax mass, recovered from the adaxial leaf surface, amounted from 0.38 μ g cm− 2 (control) up to 0.49 μ g cm− 2 (24 h). Chemical composition of surface wax altered, whereas the contact angle of applied water droplets on leaf surface of UV-B treated plants did not change significantly compared to the control. The alteration of surface wax quantity and quality significantly affected retention of a.i.; it increased at a sampling time of 24 h after UV-B irradiation, whereas rainfastness of the fungicide spray solution was not significantly influenced.

Influence of rain intensity and rapeseed oil ethoxylate adjuvants on biological efficacy of glyphosate

In order to investigate the impact of rapeseed oil ethoxylates (RSO) as tank-mix-adjuvants on the biological efficacy of glyphosate, three selected weed species (Abutilon theophrasti, Chenopodium album, and Setaria viridis) were exposed to three rain intensities (0.5 mm h−1; 5 mm h−1; 48 mm h−1) 2 h after herbicide application. Total precipitation amounted 5 mm rain in each group. In all weed species, torrential rain (48 mm h−1) caused an intense glyphosate wash-off, which could in part be reduced by addition of adjuvants. In S. viridis the addition of Rso’s did not enhance the biological activity if a heavy rain (5 mm h−1) was simulated, whereas addition of higher ethoxylated Rso’s to the spray solution resulted in reduced dry matter in C. album. In A. theophrasti the herbicidal solution containing Rso’s (except Rso 30) resulted in increased bio-performance after the heavy rain. When exposed to light rain (0.5 mm h−1), no significant differences could be established in any treatment group and weed species, except for Roundup Ultramax® in A. theophrasti. Results of biological efficacy of glyphosate solutions with or without rain exposition were analysed with respect to weed leaf micromorphology, which has been studied using a scanning electron microscope.ZusammenfassungAm Beispiel von drei ausgewählten Unkräutern (Abutilon theophrasti, Chenopodium album und Setaria viridis) sollte der Einfluss unterschiedlicher Regenintensitäten (0,5 mm h−1, 5 mm h−1 und 48 mm h−1) sowie der Zusatz von Rapsöl-ethoxylaten zu der Spritzlösung auf die biologische Wirksamkeit des Herbizids Glyphosat untersucht werden. Zwei Stunden nach der Herbizid-Applikation wurden unabhängig von der Regenintensität 5 mm Regen simuliert. Starkregen (48 mm h−1) führte bei allen Unkräutern zu einer starken Abwaschung des Spritzbelages, die zum Teil durch den Zusatz von Adjuvantien vermindert werden konnte. In S. viridis verbesserte der Ethoxylatzusatz bei Dauerregen (5 mm h−1) die Regenbeständigkeit des Glyphosats nicht, wohingegen eine zunehmende Ethoxylierung bei C. album eine steigende biologische Wirksamkeit der Glyphosatlösungen zur Folge hatte. In A. theophrasti war nach Dauerregen eine Steigerung der herbizide Wirkung des Glyphosats bei Verwendung von Rapsölethoxylaten, mit Ausnahme von Rso 30, nachweisbar. Hinsichtlich der herbiziden Wirkung besaßen bei Nieselregen alle Rso/Glyphosat-Spritzlösungen bei den 3 verwendeten Unkräutern das gleiche Signifikanzniveau. Die biologische Wirksamkeit der Glyphosatlösungen an Regen–und nicht-Regenexponierten Pflanzen wurde im Zusammenhang mit der Blattmikromorphologie der Unkräuter betrachtet.